
In the above formula 1, R represents the same or different C1-6 alkyl groups, respectively, wherein n is an integer of 6 to 12.
Recently, minimum feature size has been greatly reduced to comply with the increasing requests for large scale integration and high speed in semiconductor chips.
Silicon dioxide (SiO2, k=4.0) or fluorinated silicon oxide (k=3.5) is used as an interlayer for the large integrated and functional Al chips, there are generated a few serious problems such as signal delay due to RC delay which is indicated by a product between the resistance of a wiring material (R) and the capacitance of an insulation layer (C), and noise due to crosstalk and power loss.
Therefore, it is essential to replace the conventional aluminum wiring with copper wiring to reduce resistance of the metal wiring and also there is an urgent need for the development of an ultralow dielectric material as an insulation means. In this context, a new method has been attempted recently, wherein a thermally unstable organic material is mixed with a low dielectric inorganic matrix, proceeded further through a sol-gel reaction upon heating, and then the resulting air with dielectric constant of 1.0 is introduced into the matrix. Here, it is important that the pore-containing matrix has excellent mechanical and dielectric properties and pores with closed structure and a few nm in size.
The global trend of researches in this field can be largely divided into two groups: 1) improving the mechanical properties of the low dielectric and 2) manufacturing proper materials having a great compatibility with a matrix which results in nano-sized pores and closed pore structure.
The typical porogens are hyperbranched polyester (C. Nguyen, C. J. Hawker, R. D. Miller and J. L. Hedrick, Macromolecules, 33, 4281 (2000)), ethylene-propylene-ethylene triblock copolymer (pluonics™) (S. Yang, P. A. Mirau, E. K. Lin, H. J. Lee and D. W. Gidley, Chem. Mater., 13, 2762 (2001)), polymethylmethacrylate-N,N-dimethylaminoethyl methacrylate copolymer (Q. R. Huang, W. Volksen, E. Huang, M. Toney and R. D. Miller, Chem. Mater., 14(9), 3676 (2002)). There was also a report that nanoporous ultralow dielectric material with a dielectric constant of 2.0 or less was prepared using the above porogens.
In manufacturing the ultralow dielectric membrane using the above porogens, if the content of the porogens is low, its compatibility with inorganic matrix becomes excellent thus generating small-sized pores and allowing uniform distribution of the pores. However, as the content of the porogens increases, there occurs a proportional decrease in its compatibility with the inorganic matrix thus resulting in aggregation of porogens domains, which then leads to increase in pore size and its distribution. Thus, the produced pores shall have an interconnected structure and there will be a serious problem in the mechanical strength of the matrix and process reliability.
In order to solve the above-mentioned problems, many researches have been focused on using nano-sized inorganic particles as a template having excellent compatibility with the matrix. One of such substances is cyclodextrin having a three-dimensional cylindrical shape. The above cyclodextrin is a very small particle having a size of about 1.4 to about 1.7 nm and a relatively high melting temperature of 200° C. or higher. Furthermore, it can confer various kinds of functional groups at its terminus and thus it has advantages in terms of adjusting compatibility with its matrix. For example, the low dielectric films manufactured by mixing heptaski((2,3,6-tri-O-methyl)-β-cyclodextrin)) with cyclicsilsesquioxane (CSSQ) matrix have pores similar to those of bulks until the content of cyclodextrin is about 40% and is also reported to have a structure of closed pore (J. H. Yim, Y. Y. Lyu, H. D. Jeong, S. K. Mah, J. G. Park and D. W. Gidley, Adv. Funct. Mater., 13(5) (2003), Korea Patent Laid-Open Application No. 2002-75720). However, cyclodextrin has a low compatibility with a silicate precursor and thus dose not have a higher porosity or excellent a dielectric property. Therefore, the inventors of the present invention had previously manufactured an ultralow dielectric membrane with maximum porosity of about 60% and a relatively low dielectric constant of about 1.5 by selectively using triacetylcyclodextrin, which has an excellent compatibility with polymethylsilsequinoxane, as a template (Korea Patent Laid-Open Application No. 2003-86244).
To resolve the problem of deterioration in mechanical properties of matrix due to the introduction of pores within the inorganic low dielectric matrix, it is necessary to improve the mechanical properties of the matrix itself. This is because the low dielectric films having relatively low mechanical properties are vulnerable to harsh semi-conduct processes such as chemical mechanical planarization (CMP) thus resulting in breakage of thin films. Accordingly, the inventors of the present invention had previously manufactured a polyalkylsilsesquioxane copolymer which has a high compatibility with porogen and excellent mechanical properties by adding α,ω-bistrialkoxysilyl compound as a monomer to alkyltrialkoxysilane, which is a polymerized monomer of polymethylsilsesquioxane (Korea Patent Laid-Open Application No. 2002-38540).
The inventors of the present invention have conducted extensive researches to develop novel an organic nanoparticular porogen which can reacts with a silicate precursor. As a result, the inventors succeeded in manufacturing reactive reactive nanoparticular cyclodextrin derivatives as shown in formula 1 by allylation and hydrosilylation reactions of the cyclodextrin. Then, the inventors completed this invention by discovering that a low dielectric material having excellent dielectric properties and porosity with extremely small pore size could be manufactured by using thus manufactured nano-particles as a pore-forming template.
Therefore, an object of this invention is to provide reactive nanoparticular porogen based on cyclodextrin derivatives as shown in formula 1.
Furthermore, another object of this invention is to provide a ultralow dielectric matrix containing nano-sized pores with excellent mechanical properties, which is manufactured by performing a sol-gel reaction of the reactive cyclodextrin with the inorganic silicate precursors.
Further, still another object of this invention is to provide as a pore-forming template an ultralow dielectric composition containing reactive reactive nanoparticular porogens in an organic or inorganic silicate precursor.
Further, still another object of this invention is to provide an ultralow dielectric films with higher mechanical properties such as elastic modulus and surface hardness manufactured by additional heat-treatment at a relatively high temperature as well as a sol-gel reaction after coating the above-mentioned ultralow dielectric composition on top of a substrate.